Expression of garlic leaf lectin under the control of the phloem-specific promoter Asus1 from Arabidopsis thaliana protects tobacco plants against the tobacco aphid (Myzus nicotianae)

BACKGROUND: To check for correlation between the insecticidal properties and the specificity of lectins, a comparative study was made of the insecticidal activities of two garlic lectins with different biological activities.RESULTS: The insecticidal activity of the garlic (Allium sativum L.) leaf lectin ASAL and bulb lectin ASAII towards the tobacco aphid Myzus nicotianae Blackman was studied using bioassays with transgenic tobacco (Nicotiana tabacum L. cv. Wisconsin 38). Bioassays were started with newborn nymphs of the tobacco aphid. Although during the first 7-8 days when nymphs developed to adults there were no apparent effects, part of the nymphal population was found to develop into winged (alate) forms. Later it became clear that transgenic plants expressing ASAL and ASAII had a significant effect on the reproduction capacity of the resulting adults, with a reduction of up to 40%. Different life table parameters such as prereproductive time, intrinsic rate of natural increase, generation time and doubling time were significantly affected (P < 0.05) in aphids grown on transgenic plant material expressing ASAL and ASAII.CONCLUSION: Bioassays with tobacco plants expressing ASAL and ASAII demonstrated a significant impact on the population growth of M. nicotianae. Therefore, both lectins can be considered as valuable candidate aphid control agents.     

西安市长安区油菜田桃蚜和萝卜蚜种群空间格局的地统学分析

应用地学统计学的原理和方法研究油菜角果成熟期桃蚜及萝卜蚜种群的空间结构和空间相关性。结果表明:桃蚜种群半变异函数曲线为球型和指数模型,其空间格局为聚集型,变程范围为0.32～16.43 m;萝卜蚜种群半变异函数曲线也为球型和指数模型,呈聚集空间格局,空间变程在0.59～17.39 m。采用GS+对空间分布数据进行插值和模拟,显示桃蚜聚集程度逐渐减小,变程也随之减少;萝卜蚜的聚集程度增加,最终形成一个强聚集中心。     

峨眉千里光甲醇提取物杀虫、抑菌及抑制种子萌发活性的初步研究

本文研究了峨眉千里光甲醇提取物的杀虫、抑菌及抑制种子萌发的活性。结果表明,对甲醇提取物进一步萃取后,氯仿、乙酸乙酯及正丁醇萃取物表现出很强的杀虫、抑菌及抑制种子萌发活性,其中对桃蚜24h的LC50值在0.119~0.414mg/mL之间,对番茄灰霉病菌72h的EC50值在5.956~9.416mg/mL之间。因此,峨眉千里光甲醇提取物的氯仿和乙酸乙酯萃取物的杀虫、抑菌活性成分值得进一步深入研究。     

异色瓢虫对两种苹果蚜虫的捕食作用

为了明确异色瓢虫对两种常见苹果蚜虫绣线菊蚜(Aphis citricola Von der Goot)和苹果瘤蚜(Myzus malisuctus Matsumura)的控制作用,于2010年6月,在青岛农业大学实验室内,研究异色瓢虫成虫和4龄幼虫对两种蚜虫的捕食功能反应,同时也研究异色瓢虫4龄幼虫对两种蚜虫的捕食选择性。结果表明,异色瓢虫成虫和4龄幼虫对两种苹果蚜虫的捕食功能反应类型均属于HollingⅡ型;异色瓢虫成虫对绣线菊蚜和苹果瘤蚜的最大捕食量分别为123.91和180.98头/d,瞬时攻击率分别为1.029 1和1.335 7;4龄幼虫对绣线菊蚜和苹果瘤蚜的最大捕食量分别为128.88和187.29头/d,瞬时攻击率分别为1.156 0和1.163 4。在两种蚜虫的混合种群中,异色瓢虫4龄幼虫对苹果瘤蚜的选择效应略大于绣线菊蚜,但这种选择性差异在两种蚜虫之间并不明显。     

竹醋液对番茄生长发育及桃蚜的影响

通过种子萌发、盆栽灌根、田间喷雾等试验方法,研究不同浓度的竹醋液对番茄种子萌发、桃蚜Myzuspersicae、生长发育、果实产量及品质的影响。结果表明:(1)5 000×稀释竹醋液显著促进番茄种子萌发,500×则显著抑制番茄种子的萌发。(2)500×的竹醋液灌根显著增加了番茄的根长、株高、生物量和叶绿素含量,各种浓度对侧枝数均无显著作用。(3)田间叶面喷施300×、500×和700×的竹醋液后显著提高叶绿素含量,其它浓度对叶绿素含量无显著影响。(4)田间叶面喷施各浓度的竹醋液对桃蚜的虫口减退率在药后3 d、5 d均显著高于对照,且浓度愈高,虫口减退率也愈高。(5)田间叶面喷施500×的竹醋液后显著提高番茄产量,叶面喷施其它浓度的竹醋液对产量均无显著影响。(6)田间喷施各种浓度的竹醋液均显著降低了番茄果实中的有机酸含量;100×的竹醋液喷施后显著降低了果实中的VC含量,300×、500×、700×、1 000×和1 500×的竹醋液均显著提高了VC含量。     

不同温湿度及光照强度对烟蚜繁殖的影响

[目的]明确不同温湿度及光照强度对烟蚜繁殖的影响,提高烟蚜的繁殖效果.[方法]在不同温湿度和光照强度下培养烟蚜,对烟蚜的种群年龄结构、繁殖效果进行分析.[结果]不同温湿度和光照强度对烟蚜繁殖影响较大,在相对湿度较低、光照充足条件下有利于烟蚜生长发育,病害发生较低,繁殖效果较好.[结论]试验结果为毕节市烟蚜茧蜂防治烟蚜提供了理论依据.     

烟草蚜传病毒病发生的主要因子及预测预报模型

试验结果表明，陕西烟田蚜传病毒病的介体和初侵染毒源均来自当地冬油菜田；蚜传病毒病的主要种类有CMV、TEV和PVY；有翅桃蚜迁入烟田有2个高峰期，第1高峰期出现在5月中旬，第2高峰期出现在6月中旬；各品种之间存在着不同的耐病性，其中MsB07、MsG02耐病；以陕西泾阳1994－1998年5年的烟草病情资料、当地气象资料和相关资料建立了烟田蚜传病毒病发病率（Y）预测预报模型：Y＝－6．909＋0．011528X4＋0．0026X5＋0．001785X12＋0．448X13。     

Comparative analysis of neonicotinoid binding to insect membranes: I. A structure-activity study of the mode of [3H]imidacloprid displacement in Myzus persicae and Aphis craccivora

Neonicotinoids bind selectively to insect nicotinic acetylcholine receptors with nanomolar affinity to act as potent insecticides. While the members of the neonicotinoid class have many structural features in common, it is not known whether they also share the same mode of binding to the target receptor. Previous competition studies with [3H]imidacloprid, the first commercialised neonicotinoid, indicated that thiamethoxam, representing a novel structural sub-class, may bind in a different way from that of other neonicotinoids. In the present work we analysed the mode of [3H]imidacloprid displacement by established neonicotinoids and newly synthesized analogues in the aphids Myzus persicae Sulzer and Aphis craccivora Koch. We found two classes of neonicotinoids with distinct modes of interference with [3H]imidacloprid, described as direct competitive inhibition and non-competitive inhibition, respectively. Competitive neonicotinoids were acetamiprid, nitenpyram, thiacloprid, clothianidin and nithiazine, whereas thiamethoxam and the N-methyl analogues of imidacloprid and clothianidin showed non-competitive inhibition. The chloropyridine or chlorothiazole heterocycles, the polar pharmacophore parts, such as nitroimino, cyanoimino and nitromethylene, and the cyclic or acyclic structure of the pharmacophore were not relevant for the mode of inhibition. Consensus structural features of the neonicotinoids were defined for the two mechanisms of interaction with [3H]imidacloprid binding. Furthermore, two sub-classes of non-competitive inhibitors can be discriminated on the basis of their Hill coefficients for imidacloprid displacement. We conclude from the present data that the direct competitors share the binding site with imidacloprid, whereas non-competitive compounds, like thiamethoxam, bind to a different site or in a different mode.     

Comparative analysis of neonicotinoid binding to insect membranes: II. An unusual high affinity site for [3H]thiamethoxam in Myzus persicae and Aphis craccivora

Neonicotinoids represent a class of insect-selective ligands of nicotinic acetylcholine receptors. Imidacloprid, the first commercially used neonicotinoid insecticide, has been studied on neuronal preparations from many insects to date. Here we report first intrinsic binding data of thiamethoxam, using membranes from Myzus persicae Sulzer and Aphis craccivora Koch. In both aphids, specific binding of [3H]thiamethoxam was sensitive to temperature, while the absolute level of non-specific binding was not affected. In M persicae, binding capacity (Bmax) for [3H]thiamethoxam was ca 450 fmol mg(-1) of protein at 22 degrees C and ca 700 fmol mg(-1) of protein at 2 degrees C. The negative effect of increased temperature was reversible and hence not due to some destructive process. The affinity for [3H]thiamethoxam was less affected by temperature: Kd was ca 11 nM at 2 degrees C and ca 15 nM at 22 degrees C. The membranes also lost binding sites for [3H]thiamethoxam during prolonged storage at room temperature, and upon freezing and thawing. In A craccivora, [3H]thiamethoxam was bound with a capacity of ca 1000 fmol mg(-1) protein and an affinity of ca 90 nM, as measured at 2 degrees C. Overall, the in vitro temperature sensitivity of [3H]thiamethoxam binding was in obvious contrast to the behaviour of [3H]imidacloprid studied in parallel. Moreover, the binding of [3H]thiamethoxam was inhibited by imidacloprid in a non-competitive mode, as shown with M persicae. In our view, these differences demonstrate that thiamethoxam and imidacloprid, which represent different structural sub-classes of neonicotinoids, do not share the same binding site or mode. This holds also for other neonicotinoids, as we report in a companion article.     

桃蚜敏感种群的筛选及其抗药性演化的研究

采用微量毛细管点滴法筛选出比河北廊坊桃蚜相对敏感种群更为敏感的甘肃宕昌桃蚜种群,建立了18种杀虫剂对桃蚜敏感种群的毒力基线,可作为今后国内各地监测桃蚜抗药性水平的敏感基线。用氧乐果、氰戊菊酯及其氧乐果+氰戊菊酯对桃蚜敏感种群进行抗性选育,汰选20次时桃蚜对混剂氧乐果+氰戊菊酯只产生4.85倍的抗药性,比氧乐果单剂(7.39倍)抗性发展速度幔,尤其比氰戊菊酯单剂(87.21倍)更慢,表明桃蚜易对菊酯类药剂产生抗药性,混剂可以延缓产生抗药性。